Lawns, Gardens & Trees
During autumn, deciduous trees like green ash and linden change color and lose their leaves. This is normal and expected. It happens every year and people are used to it. When evergreen needles turn brown and die, it’s definitely unexpected, but not necessarily abnormal.
There are several species of evergreens or conifers that grow in North Dakota. Pines and spruces are most common. Pines have relatively long needles (two to nine inches), which are held in clusters called fascicles. These needles live for two to seven years and then die and drop during the fall. These are the older needles toward the center of the tree. Needles that are going to drop start turning yellow as early as late August. By mid-September these needles turn brown and begin falling from the tree.
Another common group of conifers are the spruces such as Colorado blue spruce and Black Hills spruce. These trees have shorter needles, about three-quarter to an inch long, and are attached to the stem individually, not in bundles. Spruce needles usually live longer than pine needles and may persist for up to 10 years. Just like pines, those spruce needles which are older and more shaded, will turn color and drop during autumn. In the photo, the ponderosa pine (background) is showing normal fall coloration, while the Colorado blue spruce (foreground) is not shedding any of its needles.
Some needle drop by conifers during the fall is normal. The exception occurs with larch trees (also called tamarack). Larch trees lose all of their needles every year because they are deciduous evergreens. Larch needles are one to two inches long and borne in clusters on short shoots or individually on long shoots. The needles are also very soft. Some larch trees are native to the swamps and bogs of northern Minnesota. A common larch that has been widely planted in North Dakota is the Siberian larch. Larch needles turn bright yellow and provide a golden rain during autumn.
Evergreen needles don’t last forever. Some needle loss toward the center of the tree during autumn is normal. Needle loss at other times of the year is not normal and may be due to an insect or fungal pest or the result of severe environmental stress. Larch trees, the exception to the rule, lose all of their needles every year. Enjoy the colors this fall.
There is a new plant appearing in North Dakota landscapes and it is grabbing a lot of attention. It's diervilla (Diervilla sessilifolia). I've never heard of it before—have you?
Originally considered nothing more than a tough shrub for riverbanks and roadsides, new selections of diervilla are generating excitement across the nation.
Michael Dirr, one of the most respected woody ornamentals experts in the USA, originally dismissed diervilla but now admits he was wrong. Start with First Editions® Cool Splash® (top photo). Dirr states Cool Splash® definitely has the “wow factor!” The creamy white and green variegated leaves are bright, clean and do not burn. Cool Splash® is hardy to Zone 3.
Proven Winners Kodiak™Orange diervilla is just as special but in a much different way. Its orange-red hues glow in fall (bottom photo) and rival the beauty of burning bush. It is hardy to Zone 4.
Diervilla has light yellow flowers that attract bees and butterflies in summer. It is a thick, suckering shrub that grows 3–4 feet high and spreads 4–5 feet wide. Diervilla seems well-suited to grow in masses in low-maintenance, naturalized settings. It is resistant to deer.
Dirr reports diervilla is a “tremendously tough” plant that is tolerant to winds and drought. This sounds great for us in North Dakota!
Cool Splash® can be planted in sun but is often used as an understory plant in partial shade, where its white leaf tones are bright and dramatic. It makes sense to plant Kodiak™Orange in full sun where it develops its optimal fall color.
Diervilla is a tough shrub with striking beauty. Look for these and other hardy selections of diervilla in the future.
Written by Tom Kalb, Extension Horticulturist, North Dakota State University. Photos courtesy of Bailey Nurseries, Inc. and Proven Winners. This article was originally published in the NDSU Yard & Garden Report, September 2, 2015. Source used for this article: Dirr, M.A, 2009. Manual of woody landscape plants. 6th ed. Stipes Publishing: Champaign, IL.
The undisturbed prairies of North Dakota were once a haven for bees, but the landscape of our state is changing. The oil boom, increased pesticide use and an onslaught of mites are threatening bees. We can no longer take these insects for granted.
Bees are vital for a productive garden. We need them for cucumbers, melons and squash. We need them for berries, apples, cherries and other popular fruits.
We can take steps to make our landscapes bee friendly. Bees are just like every other creature on earth. They need food, water and a safe shelter.
Bees need food. Grow lots of different flowers. Bees will forage on flowers from the first crocus in spring until the last aster in fall (photo). Native plants are especially well suited for attracting native bees and other pollinators.
Preferred perennials include beebalm, blazing star, blanketflower, goldenrod and aster. Useful annuals include sunflower, salvia and snapdragon. Herbs such as borage, basil and chives are welcome.
Bees need water. Bees will drink from rims of bird baths. A piece of wood in the bath can serve as a landing platform for bees. You can make a bee bath by placing a shallow plate on the ground, lining it with rocks.
Bees need a safe shelter. Bees generally do not need help in constructing nests, but bee houses are easy to construct. Many bees nest in soil so allow some bare patches in the garden.
Avoid insecticides. Dust and wettable powder formulations are especially dangerous because they collect in the hair of bees. Insecticides that are relatively safe for bees include Bacillus thuringiensis, neem and horticultural oils. Chemicals should be applied in the evening when bees are not active. Avoid products with long residual activity such as soil drenches of imidacloprid.
The Xerces Society is a good source of information on attracting pollinators.
Written by Tom Kalb, Extension Horticulturist, North Dakota State University. Information was taken from an article published in the NDSU Yard & Garden Report, July 31, 2015. The photo was made available under a Creative Commons license specified by the photographer: Michael Frank Franz. Source used for this article: Stack, L.B., F. Drummond and A.C. Dibble. 2000. How to create a bee-friendly landscape.Univ. of Maine: Orono.
Chrysanthemum is the superstar of autumn—no other flower can match its brilliance in the late season.
That said, there is nothing brilliant about a perennial that blooms for only one year. Many mums planted this fall will not survive our winter.
Why not grow a fall bloomer that thrives in North Dakota? Something that will bloom this fall—and next fall.
Sedum is one of the most drought-tolerant, low-maintenance, hardy plants available. It’s perfect for North Dakota and is especially well-suited for harsh, rocky soils. It’s no wonder it is nicknamed stonecrop.
Sedum has year-round appeal. In spring and summer, its thick leaves provide an attractive foil to other flowers. Once autumn arrives, its pink flowers command our attention while other flowers in the garden fade. You will notice that bees and butterflies are drawn to sedum blooms. In winter, birds hop on top of the flower clusters and poke at the seeds.
Sedum is a staple plant of every rock garden but it will grow in any well-drained spot. They are effective when planted in groups, along borders or as a large groundcover.
‘Neon’ is a very popular sedum. Its magenta blooms are absolutely brilliant. ‘Autumn Joy’ has been an attractive and consistent performer for decades. Autumn Charm™ is a sport of ‘Autumn Joy’ with variegated leaves (shown). Wow!
The latest series of sedum are the Sunsparklers®. These compact plants come in vivid shades of red, purple and green. The creeping, 8-inch-tall plants are adorned with deep pink flowers in autumn. They are hardy to Zone 4.
Fall is coming and chrysanthemums will soon be appearing at garden centers. Enjoy them, but also keep in mind there are more reliable fall-blooming perennials for us in North Dakota: sedums.
Written by Tom Kalb, Extension Horticulturist, North Dakota State University. Photo courtesy of Bailey Nurseries, Inc. Additional photos are available in the August 23, 2015 edition of the NDSU Yard & Garden Report.
Do you want to improve the soil in your garden? Add organic matter. Organic matter is so valuable it is sometimes called “black gold” by gardeners.
The addition of organic matter will improve nearly every soil. In clay soils, organic matter breaks open the ground, allowing for better drainage and aeration. In sandy soils, organic matter helps soil to hold onto nutrients and water. Organic matter adds nutrients too.
You can add organic matter to your soil by sowing a cover crop now. These crops will blanket the soil and protect it from eroding over winter. Cover crops will capture nutrients deep in the soil and bring the nutrients near the surface for next year’s crop. Cover crops can collect snow, improve drainage and reduce weeds in the future.
Cover crops can be sown in any area of the garden that is finished producing vegetables. You can also sow between the rows of crops that are still producing.
At this time of year there are two strategies for growing cover crops:
Oats (Avena sativa) should be sown now. The oats will put on good growth this fall and die over winter. It will be easily tilled into the soil in spring or mowed and left as a mulch. This is a good option for land where you plan on growing early spring crops such as carrot, spinach and pea. Annual ryegrass (Lolium multiflorum) is an alternative to oats.
Winter rye (Secale cereale) can be planted anytime in September (the sooner, the better). Winter rye will grow vigorously this fall and begin growing again in spring. This is a good strategy for land that will be planted late in spring with warm-season crops (tomato, cucumber and squash). Mow and then cultivate the rye into the soil in early May. No-till gardeners can spray it with glyphosate in spring to kill it. Give it a couple weeks to break down and then plant your crops at the end of the month. Winter wheat (Triticum aestivum) is an alternative to winter rye.
Seeds are available from catalogs and farm supply stores. Sow oats at 4 oz., winter rye and winter wheat at 3 oz., and annual ryegrass at 2 oz. per 100 square feet.
Written by Tom Kalb, Extension Horticulturist, North Dakota State University. The photo was made available under a Creative Commons license specified by the photographer: Natural Resources Conservation Service. This article was originally published in the NDSU Yard & Garden Report. Sources used for this article: Cornell University. 2013. Improve your soil with cover crops. Ithaca, NY; and Johnny's Selected Seeds. 2015. Cover crops comparison. Albion, ME.
The grand tree of North Dakota is making a comeback.
The arching branches of elms once lined our city streets like columns in a cathedral. The majestic trees provided rapid and comforting shade over our neighborhoods.
The invasion of Dutch elm disease (DED) changed everything. Discovered in Mandan in 1969, the disease has killed thousands of elms throughout our state.
What a great loss—and these losses continue as DED spreads.
There is hope. We’ve learned how to manage DED. Trained arborists can identify infected trees quickly and dispose of the wood before the pathogen spreads.
There has been amazing progress in the introduction of new elms that resist Dutch elm disease. Dutch elm disease actually came from Asia, and some Asian elms have developed genetic resistance to it. This includes the Japanese elm cultivar ‘Discovery’. It is hardy, drought tolerant, relatively short (35–40 feet) and has an upright habit.
The University of Wisconsin and Morton Arboretum (Chicago) have incorporated the DED-resistance of Asian elms into American elms and released ‘Cathedral’ and Triumph™, respectively. These trees retain the arching habit of American elms and the disease resistance of Asian elms.
Researchers estimate that less than 1 out of every 100,000 American elms is resistant to DED. In spite of those dismal odds, a few gems that resist the pathogen have been discovered.
Dutch elm disease destroyed a group of elms along the Wild Rice River near Fargo. In this grove of death, one tree stood tall and healthy. Today we call that tree Prairie Expedition® elm, with proven resistance to the disease. Look for this tree in your nursery (municipalities are buying as many as possible). Other American elms with exceptional resistance to DED are St. Croix™ and ‘Jefferson’.
No elm is immune to DED. Use varieties that resist DED and keep them growing vigorously. Vigorous trees fight disease better than weak trees. Train elm trees when young to prevent weak, narrow crotches.
For more information on growing elms in North Dakota, watch NDSU Researcher Greg Morgenson’s 2014 talk on new elm cultivars.
Written by Tom Kalb, Extension Horticulturist, North Dakota State University. The photo was made available under a Creative Commons license specified by the photographer: Dendroica cerulea. This article was originally published in the NDSU Yard & Garden Report. Source used for this article: Gillman, J., C. Giblin, G. Johnson, E. Sagor, M. Reichenbach and G. Wyatt. 2014. Elm trees – Dutch elm disease resistant varieties. Univ. of Minnesota: Twin Cities.
Monarchs in North Dakota are happy today. They are feeding and breeding in our flower-filled prairies and gardens.
Everyone loves monarchs for their bright orange wings and gentle habits. I invite you to take a closer look at this insect and you will find a true marvel of nature:
No other insect on earth can match the migration of the monarch. In late August, the monarchs of North Dakota begin a round-trip pilgrimage to Mexico covering over 5,000 miles. They will soar in the skies like hawks, gliding 25 miles or more a day. Remarkably, they will arrive to the same villages and even the same trees their great-grandparents visited the year before.
Did you know monarchs can scare away predators that are over 100 times their size? Imagine that! They gain these powers by eating and storing toxins from milkweed in their bodies. Many birds, lizards and other predators have evolved to avoid monarchs due to these toxins.
Monarchs are amazing creatures but also very fragile. Their populations have declined by 80% over the last 20 years. This is due to many factors including the loss of overwintering sites in Mexico. In the USA they have lost breeding habitats due to agricultural expansion. The development of herbicide-tolerant crops has led to major increases in herbicide use and eliminated milkweed patches growing in pockets of farm fields where it once grew abundantly.
We can restore populations of monarchs by growing ornamental milkweeds (Asclepias spp.) in our gardens. Swamp milkweed is shown above. Monarchs cannot survive without milkweed. They lay eggs in milkweed, eat milkweed as caterpillars for its nourishment and protective toxins, and consume milkweed nectar as butterflies.
Besides growing a few milkweeds, try to reduce the unnecessary use of poisonous insecticides. These chemicals threaten monarchs, pollinators and other beneficial insects.
Written by Tom Kalb, Extension Horticulturist, North Dakota State University. The photo was made available under a Creative Commons license specified by the photographer: Brad Smith. This article was originally published in the NDSU Yard & Garden Report. Source used for this article: Oberhauser, K. 2015. University of Minnesota Monarch Lab. Univ. of Minnesota: Twin Cities.
The first colors of autumn are beginning to show and they are brilliant! The seed pods of Hot Wings® tatarian maple are blazing.
Selecting trees for fall color is a challenge for us in North Dakota. The finest trees in autumn, including most maples, struggle here. Our soils are too dry and alkaline.
Tatarian maple is an exception. It tolerates even our harsh soils and is hardy throughout the state.
Its seed pods (samaras) appear as fiery red wings. These wings contrast beautifully against the deep green foliage. Magnificent!
Tatarian maple is a small tree, growing only about 20 feet tall and wide. Its upright, spreading habit makes it an outstanding accent tree in small yards. Hot Wings® is a selection of tatarian maple noted for its radiant seed pods, vivid fall color, and strong tree structure.
If you love maples, get an analysis of your soil. If your pH is acidic to near neutral (approx. 7.2 or below), you can grow the superstars of autumn: red and sugar maples.
Superior red maples include Northfire® and ‘Northwood’. Fall Fiesta® and Northern Flare® are great sugar maples admired for their gold and orange colors. Autumn Blaze® has red maple heritage and is the leading Freeman maple.
For more information, watch the presentation on Hardy Maples for North Dakota Landscapes by NDSU Woody Plants Researcher Greg Morgenson.
Written by Tom Kalb, Extension Horticulturist, North Dakota State University. Photo courtesy of Bailey Nurseries, Inc. Article was originally published in the NDSU Yard & Garden Report.
North Dakota is a land of prairie grasses. Our soils and climate are made for growing grasses. That’s one reason why ornamental grasses are perfect for us. They are loaded with other great features too:
Ornamental grasses are easy to maintain. They rarely need watering or fertilizing. Just cut the plants back every spring—that’s it!
They have almost no pest problems. Insects or diseases rarely bother ornamental grasses. Believe it or not, deer don’t like them! That’s too good to be true!
They grow fast. Many grasses will grow up to their mature height, even up to 8 feet, within two growing seasons.
They look good all year. You’ll enjoy a changing canvas of color from the emergence of tender grass in the spring to a display of roughened textures and brilliant colors in fall and winter. As a bonus, their seed heads attract lively and colorful birds to our yards.
‘Karl Foerster’ feather reed grass is one of the most popular perennials grown today (see photo). Plants grow 5 feet tall and provide a striking vertical dimension to flower beds. Its carefree habit has made it a staple in low-maintenance landscapes. Other popular feather reed grasses include ‘Overdam’ and ‘Avalanche’, each with eye-catching variegated leaves.
‘Northwind’ switchgrass was awarded the prestigious Perennial Plant of the Year award in 2014 (‘Karl Foerster’ won in 2001). ‘Northwind’ has olive-green foliage and a sturdy, upright habit. Another showy switchgrass is ‘Shenandoah’, noted for its stunning burgundy leaves and plumes in autumn.
Written by Tom Kalb, Extension Horticulturist, North Dakota State University. The photo was made available under a Creative Commons license specified by the photographer: daryl_mitchell. More photos are available in the NDSU Yard & Garden Report.
Fireblight is a common disease of many Rose-family species in North Dakota. The list of hosts includes apples, crabapples, hawthorn, mountain-ash, cotoneaster, pear and others. Fireblight is caused by a bacteria that enters the tree via succulent tissue or through fresh wounds. The recent storms that have been rolling through our region have resulted in perfect conditions for this disease to flourish.
The most common symptoms (see below) are dead branch tips with leaves still attached, curved over at the tip into a ‘shepherd’s crook’. There is usually a sharp dividing line between living and dead tissue, and in some cases a sunken canker will be found here. The bacteria can be found even further into the living tissue which is very important when treating the problem.
A heavy infection of fireblight on a crabapple in Valley City, ND.
Dormant-season pruning is the best option for treating fireblight. Locate the dividing line between living and dead tissue, and go back at least 8-12” into the healthy wood before pruning at a branch connection. If there are just a few dead branch tips, they can be pruned out during the growing season but it is critical to sterilize the pruning tool between cuts to minimize the potential for spreading the bacteria to new wounds. Pine Sol® or a 20% bleach solution can be used as sterilizing agents. Both are corrosive to metal, so rinse and oil pruning tools when finished. Chemical treatments in the spring can help prevent the disease from establishing, and copper-based fungicides as well as streptomycin are labeled for this purpose. Follow all label directions and treatment recommendations.
Canker margin on fireblight; living tissue is on the left and dead tissue is on the right. Pruning should be at least 8-12" into living wood and should occur at a branch connection.
One additional way to prevent fireblight is plant resistant varieties of the host species. Fireblight ratings of several edible apple varities can be found at: https://www.ag.ndsu.edu/pubs/plantsci/hortcrop/h327.pdf. More information on the basics of tree pruning is available at: